Gas turbine equipment utilizing high humidity

ABSTRACT

A gas turbine equipment includes a humidifying device for humidifying compressed gas for combustion, a heat recovery device for recovering exhaust heat from a gas turbine or the compressed air so as to heat humidifying water in the humidifying device, a recuperator for recovering exhaust heat from the gas turbine and heating the compressed gas for combustion, a dehumidifying device for dehumidifying and recovering moisture in the exhaust gas having passed through the recuperator, and an exhaust gas reheater for heating the exhaust gas after dehumidification, a temperature measuring device for measuring a temperature of the exhaust gas passing through the exhaust gas reheater, and a heating temperature adjusting device for increasing the heating temperature of the exhaust gas reheater.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a gas turbine equipment utilizing highhumidity, and in particular, to a gas turbine equipment utilizing highhumidity comprising an exhaust gas reheater on the combustion gasexhaust side for preventing generation of white smoke.

2. Description of the Related Art

In general, in a gas turbine equipment utilizing high humidity, shouldexhaust gas be directly discharged into the atmosphere from a smokestackor the like, since a moisture falls in a saturated condition at atemperature of about 40 degrees C., the moisture in the exhaust gaswould be condensed resulting in generation of white smoke. In order toprevent generation of such white gas, the exhaust gas is heated justbefore discharging it into the atmosphere, as disclosed in PatentDocument 1, JP-A-2000-282894.

The technology disclosed in Patent Document 1 is effective when the gasturbine equipment is operated in a steady state or in a stable ambientair temperature condition, but since a heat quantity sufficient forpreventing generation of white smoke cannot be applied to the exhaustgas upon a start of the gas turbine equipment or during the winterseason, the generation of white smoke cannot be sufficiently prevented.Meanwhile, should the heating temperature of the exhaust gas be set to ahigher temperature in view of the start of the gas turbine equipment oroperation during the winter season, excessive heat would be applied tothe exhaust gas during the summer season, resulting in radiation ofextra heat. As a result, thermal efficiency would be lowered.

BRIEF SUMMARY OF THE INVENTION

A first object of the present invention is to provide a gas turbineequipment utilizing high humidity, which is capable of preventinggeneration of white smoke throughout a year.

A second object of the present invention is to provide a gas turbineequipment utilizing high humidity which can prevent generation of whitesmoke throughout a year, and as well can restrain radiation of extraheat so as to prevent lowering of thermal efficiency.

To the ends, according to the present invention, there is provided a gasturbine equipment utilizing high humidity, comprising a humidifier forhumidifying compressed air for combustion, a heat recovery device forrecovering exhaust heat from a gas turbine or the compressed air so asto raise a temperature of humidifying water in the humidifier, a heatrecovery device for recovering exhaust heat from the gas turbine so asto raise a temperature of the compressed air for combustion, which hasbeen humidified by the humidifier, a dehumidifier for removing andrecovering moisture from the exhaust gas having passed through the heatrecovery device, and an exhaust gas reheater for heating the exhaust gasafter dehumidification, characterized by further comprising atemperature measuring means for measuring a temperature of the exhaustgas passing through the exhaust gas reheater, and a heating temperatureadjusting means for raising the heating temperature of the exhaust gasreheater if a temperature of the exhaust gas measured by the temperaturemeasuring means is not higher than a predetermined value.

With the configuration as stated above, since the heating temperature ofthe exhaust gas reheater may be controlled in accordance with avariation in exhaust gas temperature throughout a day and a year, theexhaust gas temperature can be controlled according to the ambient airtemperature change, and as a result, generation of white gas may beprevented throughout a year, and further, radiation of extra heat may berestrained, thereby it is possible to prevent lowering of the thermalefficiency of the gas turbine equipment utilizing high humidity.

As stated above, according to the present invention, there may beprovided a gas turbine equipment utilizing high humidity, which canprevent generation of white smoke throughout a year, and which canrestrain radiation of extra heat so as to prevent lowering of thethermal efficiency thereof.

Other objects, features and advantages of the invention will becomeapparent from the following description of the embodiments of theinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF DRAWING

FIG. 1 is a block diagram illustrating a gas turbine power plantequipment utilizing high humidity, which is an embodiment of a gasturbine equipment utilizing high humidity according to the presentinvention;

FIGS. 2A to 2C are charts which show a supply water temperature, a waterspray temperature and a quantity of flow, a generation power and a powergeneration efficiency with respect to a revolution speed of arecirculation pump:

FIG. 3 is a chart which shows a relationship between generation of whitesmoke and avoidance of generation thereof, and

FIG. 4 is a block diagram illustrating a gas turbine power plantequipment utilizing high humidity, which is another embodiment of thegas turbine equipment utilizing high humidity, according to the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Explanation will be hereinbelow made of a gas turbine power plantequipment utilizing high humidity, which is an embodiment of a gasturbine equipment utilizing high humidity, according to the presentinvention, with reference to FIG. 1.

The gas turbine power plant equipment utilizing high humidity accordingto this embodiment of the present invention comprises a gas turbine 1,an air compressor 2 and a generator 3 coaxial with the former, and acombustor 4. Air a sucked into the air compressor 2 is compressed so asto be turned into a compressed air b having a high temperature, then isdischarged, and is cooled in the air cooler 5 before it is introducedinto a humidifying tower 6, which is a humidifier. Air c humidified inthe humidifying tower 6 is led through a recuperator 7 constituting aheat recovery unit so as to be heated, and accordingly, it is turnedinto a compressed air d for combustion which is jetted into thecombustor. The combustor 4 is connected thereto with a fuel supply pipe8 for feeding fuel, and accordingly, the fuel fed through this fuelsupply pipe 8 is mixed with the compressed air d for combustion and isburnt.

Combustion gas e burnt in the combustor 4 is fed into the gas turbine 1which is therefore driven so as to rotate the air compressor 2 and thepower generator 3. Exhaust gas f having passed through the gas turbine 1is led through the recuperator 7 so as to carry out heat-exchange inorder to heat the humidified air c, and is emitted into the atmospherefrom a smokestack 12, after passing through an economizer 9 constitutinga heat recovery unit, a water recovery unit 10 constituting adehumidifier for recovering moisture contained in the exhaust gas f, andan exhaust gas reheater 11 for heating the exhaust gas after recovery ofmoisture.

The humidifying tower 6 has therein a packing 13 for retaining water andfor allowing air to pass therethrough, and reserves, in its bottom part,humidifying water 14. A part Al of the humidifying water 14 in thebottom part of the humidifying tower 6 is led through a pipe line 16 andis fed so as to heat the exhaust gas after moisture recovery in theexhaust gas reheater 11 by means of a humidifying tower circulation pump15. Water B having passed through the exhaust gas reheater 11 so as tolower its temperature is heated by the exhaust gas f in the economizer9, and the heated water C1 is sprayed by a sprayer 18 provided in theupper part of the inside of the humidifying tower 6 after passingthrough a pipe line 17. A water liquid film formed over the outersurface of the packing 13 by displaying of the heated water C1, is madeinto direct contact with the compressed air b which has be led into thetower 6 by way of the air cooler 5, and accordingly, the heated water isevaporated so as to humidify the compressed air b.

Meanwhile, the other part A2 of the humidifying water 14 fed out by thehumidifying tower circulation pump 15 cools in the air cooler 5 thecompressed air b which has been compressed and heated up so as to absorbheat. The heated water C2 is then led through a pipe line 19 and to thesprayer 18 side of the pipe line 17, and is sprayed into the humidifyingtower 6 from the sprayer 18.

It is noted that the above-mentioned water recovery unit 10 is adaptedto replenish the humidifying tower 6 with the humidifying water 14 bymeans of a recovery water feed pump 20. Further, the exhaust gasdischarged from the economizer 9 has a high humidity of about 20% byweight, and accordingly, should such exhaust gas be directly emittedfrom the smokestack 12, it would be condensed within the smokestack 12or would generate white smoke. Thus, in order to prevent these problems,the water recovery unit 10 recovers moisture in the exhaust gas byspraying the water from a top thereof, by way of a recovery watercirculation pump 21, a recovery water cooler 22 and a sprayer 23.Further, the water which has been lost during the recovery isreplenished with a make-up water pump 24.

By the way, the exhaust gas having passed through the water recoveryunit 10 falls in a saturated condition at a temperature of 40 degreesC., and accordingly, it is heated in the exhaust gas reheater 11 by thepart A1 of the heated humidifying water 14 from the bottom part of thehumidifying tower 6 so as to prevent generation of white smoke.

Further, in the configuration of this embodiment, a recirculation pipeline 25 is provided to connect the pipe line 17 on the outlet side ofthe economizer 9 and the pipe line 16 to the exhaust gas regenerator 11,and a recirculation pump 26 for feeding the heated water C1 to theexhaust regenerator 11 is provided on the recirculation pipe line 25.The recirculation pipe line 25 and the recirculation pump 26 constituteheating temperature adjusting means. Further, the revolution speed ofthe recirculation pump 26 is controlled by arithmetic processing means32, in accordance with a measured temperature from a temperaturemeasuring means 27 for measuring a temperature of the exhaust gas on theoutlet side of the exhaust reheater 11.

Next, explanation will be made of the operation of the above-mentionedconfiguration.

Upon a start of the gas turbine power plant equipment utilizing highhumidity, the temperature of exhaust gas emitted from the smokestack 12is, of ourse, lower, and accordingly, the recirculation pump 26 isrested in this condition. However, a temperature of the exhaust gas ismeasured by the temperature measuring means 27, and the measured resultis processed by the arithmetic processing means 32. If it is determinedthat the temperature of the exhaust gas causes generation of whitesmoke, it is instructed to drive the recirculation pump 26 at adesignated revolution speed. When the recirculation pump 26 is driven bythe instruction from the arithmetic processing means 32, as shown inFIG. 2A, in comparison with a temperature T1 of supply water beforeconfluence with a high temperature water by the part Al of thehumidifying water 14 fed into the exhaust gas reheater 11, a temperatureT2 of supply water after the confluence with high temperature water,which is flown with the heated water C1 from the economizer 9 throughthe recirculation pipe line 25 is raised as the revolution speed of therecirculation pump 26 increases. As a result, the heat value applied tothe exhaust gas may be increased, thereby it is possible to preventgeneration of white smoke.

By the way, since high temperature water is recirculated in the exhaustgas reheater 11 so that the heat value applied to the exhaust gas iscorrespondingly increased, as shown in FIG. 2B, if the quantity Q ofwater sprayed into the humidifying tower 6 is set to be constant, thetemperature T3 of sprayed water is lowered. When the temperature T3 ofthe sprayed water decreases, a value of the humidity humidifying thecompressed gas b in the humidifying tower 6 is decreased, and, as aresult, as shown in FIG. 2C, if the generation output power ismaintained to be constant, the supply quantity of the fuel for drivingthe gas turbine is increased, and accordingly, the power generationefficiency (thermal efficiency) of the generator 3 is lowered.

Accordingly, in order to prevent lowering of the power generationefficiency, the arithmetic processing means 32 finely controls therevolution speed of the recirculation pump 26 so as to adjust thequantity of flow of the heated water C1 fed from the recirculation pipeline 25 to the exhaust gas reheater 11, thereby, preventing extra heatwhich exceeds a value required for preventing generation of white smokefrom being applied to the exhaust gas. For example, in an exhaust gasemitting condition in which no white smoke is generated, the operationof the recirculation pump 26 is stopped so as to interrupt the supply ofthe heated water C1 into the exhaust gas reheater 11 in order to preventradiation of extra heat, thereby it is possible to restrain the powergeneration efficiency from being lowered.

Next, explanation will be made of prevention of generation of whitesmoke under control of the revolution speed of the recirculation pump 26along the progress from a start to a rated load operation of the gasturbine power plant equipment utilizing high humidity, as shown in FIG.3.

FIG. 3 shows the relationship between the temperature of the exhaust gasat the outlet of the smokestack 12 and the absolute humidity under theatmospheric temperature-absolute humidity condition (A), (B) indicatesan exhaust gas condition in the case of driving the recirculation pump26 during a start of the gas turbine power plant equipment utilizinghigh humidity, and (C) indicates an exhaust gas condition in the case ofno use of the recirculation pump 26 during a start of the gas turbinepower plant equipment utilizing high humidity. Further, (D) indicates anexhaust gas condition in the case of using the recirculation pump 26during rated load operation, and (E) indicates an exhaust gas conditionin the case of no use of the recirculation pump 26 during rated loadoperation.

During the start of the gas turbine power plant equipment utilizing highhumidity, if no circulation pump 26 is used, the exhaust gas is emittedunder the exhaust gas condition (C), and accordingly, the exhaust gas ismixed with the atmospheric air therearound so that both temperature andhumidity are lowered along a broken line (3) in the drawing, and theatmospheric condition (A) is finally restored. When the atmosphericcondition is being restored, an air saturation humidity curve (1) iscrossed, and accordingly, an oversaturated condition is caused,resulting in generation of white smoke.

However, when the high temperature water from the economizer 9 is fedinto the exhaust gas reheater 11 by driving the recirculation pump 26 soas to increase the temperature of the exhaust gas up to (B), thetemperature and the humidity of the exhaust gas are lowered along thebroken line (2) so as to restore the atmospheric condition (A). At thistime, the air saturation humidity curve (1) is not crossed, andaccordingly, no generation of white smoke is caused.

It is noted that since (B) has a lower limit temperature at which nogeneration of white smoke is caused during a start, though thetemperature of the exhaust gas may be increased up to a value not lessthan (B), should the temperature of the exhaust gas be merely increasedup to the value not less than (B), extra heat is applied to the exhaustgas, and corresponding radiation of the extra heat would be caused so asto lower the power generation efficiency. Thus, in the exhaust gasreheating, it is desired to heat the exhaust gas up to (B) at which nogeneration of white smoke is caused.

In the case of driving the recirculation pump 26 at a constantrevolution speed during increase of load from a start of the gas turbinepower plant equipment utilizing high humidity, the exhaust gas variesits emitting condition from (B) along the dotted line (4) in thedrawing, and during rated load operation, it is emitted in the condition(D). Meanwhile, since the temperature of the exhaust gas also increasesas the load is increased, it is such a condition that no generation ofwhite smoke is caused even in the exhaust gas condition (E) in which norecirculation pump 26 is driven. In this condition in which an excessiveheat value is applied to the exhaust gas so as to lower the powergeneration efficiency, it is satisfactory to take such a manner that therevolution speed of the recirculation pump 26 is lowered under controlso as to change the exhaust gas condition from (B) to (E) along the line(5) in the drawing, and when the rated load is obtained, the operationof the recirculation pump 26 is stopped. By controlling therecirculation pump 26 in the above-mentioned manner, the temperature ofthe supply water for reheating (the temperature of the exhaust gas) canrestrain the generation of white smoke during operation at a lowtemperature, and the temperature of the supply water for reheating (thetemperature of the exhaust gas) can prevent radiation of an extra heatduring operation at a high temperature, thereby it is possible torestrain the power generation efficiency from lowering.

By the way, although the temperature of the exhaust gas emitted from thesmokestack 12 in the above-mentioned embodiment is measured by thetemperature measuring means 27 so as to control the recirculation pump26, there may be taken such a manner that the temperature of the hightemperature water fed into the exhaust gas reheater 11 is measured inorder to control the recirculation pump 26. Further, with the provisionof an exhaust gas temperature measuring means for measuring atemperature of the exhaust gas passing through the exhaust gas reheater11, an ambient air temperature measuring means 30 for measuring anambient air temperature, and a temperature difference comparing means 31such as arithmetic processing means for comparing a temperaturedifference between temperatures measured by the ambient air temperaturemeasuring means and the exhaust temperature measuring means, there maybe taken such a manner that the recirculation pump 26 is controlled whena temperature difference not less than a predetermined value is detectedby the temperature difference comparing means.

In addition, in stead of controlling the revolution speed of therecirculation pump 26, with the provision of a recirculation flowquantity adjusting valve whose opening angle is controlled being basedupon a result of measurement by the temperature measuring means 27 onthe outlet side of the recirculation pump 26, there may be taken such amanner that an overflow pipe line is connected at one end thereofbetween the recirculation flow quantity adjusting valve and therecirculation pump 26 and at the other end to the downstream side of thepipe line 17 in order to adjust the quantity of flow.

With the use of this flow quantity adjusting mechanism, it is possibleto adjust the supply of the high temperature water into the exhaust gasreheater 11 through the adjustment of the opening angle of therecirculation flow quantity adjusting valve, and the high temperaturewater which is not necessary for the supply into the exhaust gasreheater 11 is led through the pipe line 17 and is sprayed in thehumidifying tower 6. As a result, no revolution speed control isrequired for the recirculation pump 26, and accordingly, an inexpensivepump may be used.

Further, in the configuration of the above-mentioned embodiment, if thecompressed air b in the humidifying tower 6 is fully humidified only bythe supply of the heated water C1 from the economizer 9, the air cooler5 may be eliminated.

Although explanation has been made of such a process, as stated above,that the generation of white smoke and the lowering of the powergeneration efficiency which are caused during the period from a start torated load operation of the gas turbine power plant equipment utilizinghigh humidity, are restrained, the same process is taken together withthe same equipment even in such a case that the atmospheric temperatureis low in the winter season, and accordingly, the same technical effectsand advantage may be obtained. As a result, it is possible to preventgeneration of white smoke throughout a day and a year, and radiation ofextra heat may be restrained, thereby it is possible to restrain thepower generation efficiency from lowering.

FIG. 4 is a view illustrating a gas turbine power plant equipmentutilizing high humidity in another embodiment of the gas turbineequipment utilizing high humidity according to the present invention.Like reference numerals are used to denote like parts to those shown inFIG. 1 in order to prevent duplicated explanation thereof.

The configuration of this embodiment is the same as that of theembodiment shown in FIG. 1, except that the pipe line 19 returned to thehumidifying tower 6 is connected to the pipe line 16 connected to theexhaust gas reheater 11 through the intermediary of a recirculation pipeline 28 which is provided thereto with a recirculation pump 29 whoserevolution speed is controlled in accordance with a temperature measuredby the temperature measuring means 27, and a part of the heated water C2which has been heated in the air cooler 5 is fed to the temperaturemeasuring means 27. The recirculation pipe line 28 and the recirculationpump 29 constitute heating temperature adjusting means.

With the configuration of this embodiment, if the temperature of thesupply water fed to the exhaust gas reheater 11 from the pipe line 16 islow and the temperature of the exhaust gas led to the smokestack 12 islow, according to the temperature measured by the temperature measuredmeans 27, the recirculation pumps 26, 29 are driven under control of therevolution speeds thereof. Through the control of the revolution speedsof these recirculation pumps 26, 29, the quantity of the hightemperature water fed into the exhaust gas reheater 11 is increased soas to increase the heat value applied to the exhaust gas in order torestrain generation of white gas.

Further, under such a condition that no generation of white gas iscaused, the recirculation pumps 25, 29 are rested so as to stop thesupply of the heated water C1 from the economizer 9 and the heated waterC2 from the air cooler 5 into the exhaust gas reheater 11, and thus, theradiation of extra heat into the atmosphere is restrained, thereby it ispossible to prevent lowering of the power generation efficiency.

It is noted that the air cooler 5 in the configuration of the embodimentshown in FIG. 4 is also one of the heat recovery devices according tothe present invention, and accordingly, in the case that it issufficient to humidify the compressed air b in the humidifying tower 6and to heat the exhaust gas reheater 11 by the heated water C2 passingthrough the air cooler 5, there may-also be taken such a configurationthat the economizer 9, the pipe line 17, the recirculation pipe line 25,and the recirculation pump 26 are eliminated while water B whosetemperature is lowered in the exhaust gas reheater 11 is sprayed in thehumidifying tower 6.

By the way, in the configurations of the embodiments as stated above,the heating temperature adjusting means and the heated water temperatureadjusting means for increasing the heating temperature of the exhaustgas reheater according to the present invention correspond to thearithmetic processing means 32, the recirculation pumps 26, 29 and therecirculation flow quantity adjusting valve which are controlled by thearithmetic processing means, and as well, corresponds to the air cooler5 and the economizer 9 which serves as a heat source. It is noted thatthe recuperator 7 may be also used as the heat source. Further, the flowquantity adjusting valve serving as the flow quantity adjusting meansaccording to the present invention is the recirculation flow quantityadjusting valve.

Although explanation has been made of the configurations of the aboveembodiments in which the gas turbine power plant equipment utilizinghigh humidity coupled thereto with the generator as a load, it goeswithout saying that the gas turbine power plant equipment utilizing highhumidity may drive any load other than the generator.

It should be further understood by those skilled in the art thatalthough the foregoing description has been made on embodiments of theinvention, the invention is not limited thereto and various changes andmodifications may be made without departing from the spirit of theinvention and the scope of the appended claims.

1. A gas turbine equipment utilizing high humidity, comprising ahumidifying means for humidifying compressed gas for combustion, a heatrecovery means for recovering exhaust heat from a gas turbine or saidcompressed air so as to heat humidifying water in said humidifyingmeans, a recuperator for recovering exhaust heat from the gas turbineand heating the compressed gas for combustion, which has been humidifiedby said humidifying means, a dehumidifying means for dehumidifying andrecovering moisture in the exhaust gas having passed through saidrecuperator, and an exhaust gas reheater for heating the exhaust gasafter dehumidification, wherein said gas turbine equipment furthercomprises: a temperature measuring means for measuring a temperature ofthe exhaust gas passing through said exhaust gas reheater; a heatingtemperature adjusting means for adjusting a heat value applied to theexhaust gas by said exhaust gas reheater; and arithmetic processingmeans for controlling said heating temperature adjusting means, inaccordance with a temperature of the exhaust gas measured by saidtemperature measuring means, so as to increase the temperature of theexhaust gas heated by said exhaust gas reheater to or over apredetermined value.
 2. A gas turbine equipment utilizing high humidityas set forth in claim 1, wherein said heat recovery means comprises anair cooler arranged upstream of said humidifying means, and aneconomizer arranged downstream of said recuperator.
 3. A gas turbineequipment utilizing high humidity, comprising a humidifying means forhumidifying compressed gas for combustion, a heat recovery means forrecovering exhaust heat from a gas turbine or said compressed air so asto heat humidifying water in said humidifying means, a recuperator forrecovering exhaust heat from the gas turbine and heating the compressedgas for combustion, which has been humidified by said humidifying means,a dehumidifying means for dehumidifying and recovering moisture in theexhaust gas having passed through said recuperator, and an exhaust gasreheater for heating the exhaust gas after dehumidification, whereinsaid gas turbine equipment further comprises: an exhaust gas temperaturemeasuring means for measuring a temperature of the exhaust gas passingthrough said exhaust gas reheater; an ambient air temperature measuringmeans for measuring an ambient air temperature; a temperature differencecomparing means for comparing a difference between temperatures measuredby said ambient air temperature measuring means and said exhaust gastemperature measuring means; a heating temperature adjusting means foradjusting a heat value applied to the exhaust gas by said exhaust gasreheater; and arithmetic processing means for controlling said heatingtemperature adjusting means, in accordance with a temperature differencedetected by said temperature difference comparing means, so as toincrease the temperature of the exhaust gas heated by said exhaust gasreheater to or over a predetermined value.
 4. A gas turbine equipmentutilizing high humidity as set forth in claim 3, wherein said heatrecovery means comprises an air cooler arranged upstream of saidhumidifying means, and an economizer arranged downstream of saidrecuperator.